当三相异步电动机的转差率s＞1时，电动机的工作状态是（）。A．_爱下问搜题

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问题单项选择题

当三相异步电动机的转差率s＞1时，电动机的工作状态是（）。

A．电动机

B．再生制动

C．反接制动

D．能耗制动

答案

参考答案：C

选择题

My parents ran a small restaurant in Seattle. It was open twenty-four hours a day, six days a week. And my first real job, when I was six years old, was   31  the diners’ shoes. My father had done it when he was young, so he taught me 32  to do it well, telling me to 33  to shine the shoes again if the customer wasn’t 34 .
I was proud of working in the restaurant   35 I was also working for the good of the family. But my father   36  said that I had to meet certain standards(标准) to be part of the team. I   37  to be on time, hard-working, and polite to the 38 . I was    39  paid for the work I did at the restaurant. One day I made the mistake of suggesting to Dad that he 40   give me $10 a week. He said, “OK. How about you paying me for three meals a day you have here? And for the times you bring in your friends 41  free soft drinks?” He   42  the amount of money I owed him, about $40 a week.
I remember returning to Seattle after being 43  in the US Army for about two years. I had just been promoted（升职） to Captain at that time. And full of pride, I walked into my parents’ restaurant, but the   44  thing Dad said was, “How about your   45  up tonight?” I couldn’t 46  my ears! I am an officer in the Army! But   47 didn’t matter. As far as Dad was concerned, I was just 48  member of the team. I reached for the mop(拖把).Working for Dad has taught me that the devotion(奉献) to a 49  is above all. It has nothing to do with 50  that team is for a family restaurant or the US Army.

问答题简答题

为什么烟煤粘结指数G的测定必须在煤样制备后一周内进行？